Thanks. Looks like the royal society link is the original work, but the nature editorial also mentions the same - it’s still possible we might have higher stability in other conditions (they only loooked at dna in bone samples). Not saying we will hold hope for dinosaur cloning, just that 521 years sounds too small.
Amber is heterogeneous in composition, but consists of several resinous bodies more or less soluble in alcohol, ether and chloroform, associated with an insoluble bituminous substance. Amber is a macromolecule by free radical polymerization of several precursors in the labdane family, e.g. communic acid, cummunol, and biformene. These labdanes are diterpenes (C20H32) and trienes, equipping the organic skeleton with three alkene groups for polymerization. As amber matures over the years, more polymerization takes place as well as isomerization reactions, crosslinking and cyclization.
The questions still seems reasonable? Maybe there exists some geological processes minerals deposits that absorbed moisture? Some kind of geothermal heating (although maybe that would just make steam permeate the surrounding area), an asteroid fragment from the Chicxulub impact that carried DNA into space??